1. Field of the Invention
The present invention relates generally to an apparatus and method for managing Digital Rights Management (DRM) contents in a portable terminal, and in particular, to an apparatus and method for preventing a replay attack on DRM contents.
2. Description of the Related Art
An internal memory of a portable terminal generally has a limited capacity of 32 MB or 64 MB. The internal memory is used for a built-in camera, Multimedia Message Services (MMSs), and various application programs, so that the internal memory stores still pictures, moving pictures, messages, metadata, and setting information used in the application programs. Thus, an available capacity of the internal memory has become very small.
Recently, the number of high-definition and large-capacity digital rights management (DRM) contents has increased according to users' demands. The DRM contents are encrypted contents for protecting rights and interests of digital content providers and thus a license or a right object is essential for decrypting and using the DRM contents. The license generally has a capacity of 5 to 20 KB and one DRM content may have up to one thousand licenses according to its type. Therefore, it is difficult to store a number of the DRM contents into the internal memory.
As a result, it has been recently recommended that an external memory of a portable terminal store a DRM DataBase (DB) having information on a license of a DRM content. However, when the external memory stores the DRM DB, a replay attack on usage-count and usage-time limited DRM contents is possible. For example, a DRM DB stored in an external memory is backed-up to another device, and a corresponding DRM content is used for a predetermined usage-count or usage-time, and then the backup DRM DB is again stored in the external memory. In this way, the DRM content can be continuously used regardless of the predetermined usage-count or usage-time.